Catheters are widely used by the clinical radiologist and the surgeon. In addition, catheters find application in diagnosing and treating many ailments. They are used in virtually all passageways of the body, from blood vessels and urinary tracts to nasal and throat openings. Catheters function to augment flow of blood, air, urine, or as a means of treatment through drug delivery and removal of plaque and clots.
One of the great difficulties in utilizing catheters in the vascular system relates to the control of movement of the catheter through the variously branching vessels. A common form of vascular system catheter is described in U.S. Pat. No. 3,687,142 and contains a balloon-like member which assists in "floating" the catheter along with the flow of blood. However, navigating the balloon-like member selectively into and through tortuous side vessels is quite difficult and, in many cases, impossible. Toposcopic catheter designs permit movement of the catheter through vessels but have no provision for guiding and are therefore largely limited to non-bifurcated or non-branching vessels.